Wolverine and the X-Men

This episode premiered at a special time of Sunday at 10:00pm (ET) instead of its normal timeslot of Friday at 8:00pm (ET). It premiered as a part of Nicktoons' Thanksgetting Weekend.

If Wolverine found the X-23 clones in an old Hydra compound, that would mean that either Hydra existed long after the cataclysm or that the clones were created before it occurred.

This episode premiered at a special time of Sunday at 9:30pm (ET) instead of its normal timeslot of Friday at 8:00pm (ET). It premiered as a part of Nicktoons' Thanksgetting Weekend.

Goof:
The Sentinel group entering Genosha was composed of fifteen units. When Magneto lifted them in order to change their programming, there were only ten around him. When the Sentinels are leaving the island, they are again fifteen.

This episode premiered at a special time of Sunday at 9:00pm (ET) instead of its normal timeslot of Friday at 8:00pm (ET). It premiered as a part of Nicktoons' Thanksgetting Weekend.

First appearance of the Stepford Cuckoos

According to the pop-up version of this episode, the psychic wave Jean unleashed that knocked out the entire city was a feat greater than Charles Xavier could accomplish, even with his powers amplified by Cerebro.

First appearance of the Inner Circle (Sebastian Shaw, Harry Leland, Donald Pierce, Selene) and Apocalypse

The Water Distribution Channels give water to the entire island of Genosha.

This episode premiered as part of Nicktoons Network's "Non-Stop Cyclops" Marathon. The marathon featured Cyclops-themed episodes of the series, all leading up to this one.

First appearance of the Phoenix Force. This episode also marks the first time that the original X-Men (Cyclops, Jean Grey, Iceman, Angel and Beast) have all appeared together in their original costumes.

In the comics, it was Cameron Hodge who had Angel's wings removed and it was Apocalypse who turned him into Archangel.

Character Debut:
Archangel

Character Debuts:
Silver Samurai, Mariko

In this episode, Wolverine, Forge and Shadowcat are wearing the costumes worn in the current X-Force series.

First spoken dialogue by Polaris. She is with Mystique and the Scarlet Witch behind Magneto on his dais in the conclusion of "Battle Lines", but had no lines.

First appearance of X-23.

Goof:
Throughout the episode, there are discrepancies as to when Kitty Pryde is or isn't wearing her costume.

First appearance of Juggernaut, Blink, Tildie Soames and the Kleinstocks.

First appearance of the Marauders (Harpoon, Blockbuster, Vertigo, Arclight), Mister Sinister and Multiple Man